Guanidino quinazolines and pyrimidines promote readthrough of premature termination codons in cells with native nonsense mutations.

Using small molecules to induce readthrough of premature termination codons is a promising therapeutic approach to treating genetic diseases and cancers caused by nonsense mutations, as evidenced by the widespread use of ataluren to treat nonsense mutation Duchene muscular dystrophy. Herein we describe a series of novel guanidino quinazoline and pyrimidine scaffolds that induce readthrough in both HDQ-P1 mammary carcinoma cells and mdx myotubes. Linkage of basic, tertiary amines with aliphatic, hydrophobic substituents to the terminal guanidine nitrogen of these scaffolds led to significant potency increases. Further potency gains were achieved by flanking the pyrimidine ring with hydrophobic substituents, inducing readthrough at concentrations as low as 120 nM and demonstrating the potential of these compounds to be used either in combination with ataluren or as stand-alone therapeutics.

The nucleoside analog clitocine is a potent and efficacious readthrough agent.

Nonsense mutations resulting in a premature stop codon in an open reading frame occur in critical tumor suppressor genes in a large number of the most common forms of cancers and are known to cause or contribute to the progression of disease. Low molecular weight compounds that induce readthrough of nonsense mutations offer a new means of treating patients with genetic disorders or cancers resulting from nonsense mutations. We have identified the nucleoside analog clitocine as a potent and efficacious suppressor of nonsense mutations. We determined that incorporation of clitocine into RNA during transcription is a prerequisite for its readthrough activity; the presence of clitocine in the third position of a premature stop codon directly induces readthrough. We demonstrate that clitocine can induce the production of p53 protein in cells harboring p53 nonsense-mutated alleles. In these cells, clitocine restored production of full-length and functional p53 as evidenced by induced transcriptional activation of downstream p53 target genes, progression of cells into apoptosis, and impeded growth of nonsense-containing human ovarian cancer tumors in xenograft tumor models. Thus, clitocine induces readthrough of nonsense mutations by a previously undescribed mechanism and represents a novel therapeutic modality to treat cancers and genetic diseases caused by nonsense mutations.

Ataluren stimulates ribosomal selection of near-cognate tRNAs to promote nonsense suppression.

A premature termination codon (PTC) in the ORF of an mRNA generally leads to production of a truncated polypeptide, accelerated degradation of the mRNA, and depression of overall mRNA expression. Accordingly, nonsense mutations cause some of the most severe forms of inherited disorders. The small-molecule drug ataluren promotes therapeutic nonsense suppression and has been thought to mediate the insertion of near-cognate tRNAs at PTCs. However, direct evidence for this activity has been lacking. Here, we expressed multiple nonsense mutation reporters in human cells and yeast and identified the amino acids inserted when a PTC occupies the ribosomal A site in control, ataluren-treated, and aminoglycoside-treated cells. We find that ataluren's likely target is the ribosome and that it produces full-length protein by promoting insertion of near-cognate tRNAs at the site of the nonsense codon without apparent effects on transcription, mRNA processing, mRNA stability, or protein stability. The resulting readthrough proteins retain function and contain amino acid replacements similar to those derived from endogenous readthrough, namely Gln, Lys, or Tyr at UAA or UAG PTCs and Trp, Arg, or Cys at UGA PTCs. These insertion biases arise primarily from mRNA:tRNA mispairing at codon positions 1 and 3 and reflect, in part, the preferred use of certain nonstandard base pairs, e.g., U-G. Ataluren's retention of similar specificity of near-cognate tRNA insertion as occurs endogenously has important implications for its general use in therapeutic nonsense suppression.

PTC124 targets genetic disorders caused by nonsense mutations.

Nonsense mutations promote premature translational termination and cause anywhere from 5-70% of the individual cases of most inherited diseases. Studies on nonsense-mediated cystic fibrosis have indicated that boosting specific protein synthesis from <1% to as little as 5% of normal levels may greatly reduce the severity or eliminate the principal manifestations of disease. To address the need for a drug capable of suppressing premature termination, we identified PTC124-a new chemical entity that selectively induces ribosomal readthrough of premature but not normal termination codons. PTC124 activity, optimized using nonsense-containing reporters, promoted dystrophin production in primary muscle cells from humans and mdx mice expressing dystrophin nonsense alleles, and rescued striated muscle function in mdx mice within 2-8 weeks of drug exposure. PTC124 was well tolerated in animals at plasma exposures substantially in excess of those required for nonsense suppression. The selectivity of PTC124 for premature termination codons, its well characterized activity profile, oral bioavailability and pharmacological properties indicate that this drug may have broad clinical potential for the treatment of a large group of genetic disorders with limited or no therapeutic options.

Oncologic outcomes after laparoscopic versus open multivisceral resection for local advanced colorectal cancer: A meta-analysis.

Laparoscopic (lap) colectomies for advanced colorectal cancer (CRC) often require resection of other organs. We systematically reviewed currently available literature on lap multi-visceral resection for CRC, with regard to short- and long-term oncological outcomes, and compared them with open procedures. We performed a systematic literature search in MEDLINE, EMBASE, Google Scholar and PubMed from inception to November 30, 2020. The aim of this study was to synthesize short-term and oncological outcomes associated with laparoscopic versus open surgery. Pooled proportions and risk ratios (RRs) were calculated using an inverse variance method. We included six observational cohort studies published between 2012 and 2020 (lap procedures: n = 262; open procedures: n = 273). Collectively, they indicated that postoperative complications were significantly more common after open surgeries than lap surgeries (RR: 0.53; 95% confidence interval [CI]: 0.39-0.72; P < 0.00001), but the two approaches did not significantly differ in positive resection margins (RR: 0.75; 95% CI: 0.38-1.50; P = 0.42), local recurrence (RR: 0.66; 95% CI: 0.28-1.62; P = 0.37), or (based on two evaluable studies) 5-year OS (RR: 0.70; 95% CI: 0.46-1.04; P = 0.08) or 5-year DFS (RR: 0.86; 95% CI: 0.67-1.11) for T4b disease. In conclusion, laparoscopic and open multi-visceral resections for advanced CRC have comparable oncologic outcomes. Although a randomized study would be ideal for further research, no such studies are currently available.

Initial entry via the left upper quadrant with an optical trocar in laparoscopic bariatric surgery.

INTRODUCTION: Laparoscopic bariatric surgery (BS) is not readily performed in Japan. To facilitate safe initial access to the abdominal cavity, we insert an optical viewing trocar at a unique site in the left upper quadrant (LUQ). Herein, we describe the technique, its advantages, and outcomes. MATERIALS AND SURGICAL TECHNIQUE: Briefly, the optical trocar is inserted just below the left subcostal margin, 8 cm from the midline. On insertion, layers of the abdominal wall are visualized on the monitor. Depending on the angle of insertion, five, seven, or eight layers are seen. DISCUSSION: In assessing our initial entry technique, used in 21 obese patients undergoing laparoscopic sleeve gastrectomy, we found median insertion time to be 25 seconds. There were no related complications. In nearly all (20/21) patients, the abdominal wall was visualized as seven layers: subcutaneous fat, anterior rectus sheath, rectus abdominis muscle, posterior rectus sheath, transverse abdominis muscle, transversalis fascia, and peritoneum. Understanding the layers of the abdominal wall visualized during optical trocar insertion in the LUQ will provide for safe and rapid initial entry in patients undergoing laparoscopic BS and can further the widespread acceptance of laparoscopic BS.

Successful one-stage laparoscopic procedure for de Garengeot hernia: a totally extraperitoneal repair-first approach.

The de Garengeot hernia is a femoral hernia in which the appendix migrates into the hernia sac. It is usually diagnosed intraoperatively due to its rarity and lack of clinical presentation typical to acute appendicitis. Although most cases need emergency operation due to incarceration, no standard procedure exists. We report the case of a 49-year-old woman who was diagnosed with a de Garangeot hernia preoperatively by contrast-enhanced computed tomography. She underwent one-stage laparoscopic surgery via a totally extraperitoneal approach followed by laparoscopic appendectomy. She recovered uneventfully and was discharged on postoperative Day 3. Generally, hernioplasty and appendectomy are required for the de Garengeot hernia treatment. Avoiding a peritoneal incision around the herniation and performing a mesh repair prior to appendectomy is expected to carry a lower infectious risk than other laparoscopic procedures. With accurate diagnosis, this procedure could be a useful modality for de Garengeot hernia.

Laparoscopic transabdominal preperitoneal hernioplasty for recurrent obturator hernia: A case report.

Reports of recurrence after obturator hernia repair are few. We describe the case of an 89-year-old woman who presented to us with a thrice recurrent obturator hernia. She had undergone open non-mesh repair twice and then laparoscopic non-mesh repair. She was readmitted to our hospital 6 months after the laparoscopic repair. Manual reduction was successful, paving the way for elective transabdominal preperitoneal repair. During the endoscopic repair, surgical mesh was placed extraperitoneally over the hernia defect and then fixed to Cooper's ligament with absorbable tacks. The patient was discharged on postoperative day 2 without complications. In the 2 months that have passed since the surgery there has been no sign of recurrence, but the patient will be carefully followed up. Repair of a recurrent obturator hernia is technically challenging; however, the transabdominal preperitoneal approach seems to be reliable and safe.

The minor gentamicin complex component, X2, is a potent premature stop codon readthrough molecule with therapeutic potential.

Nonsense mutations, resulting in a premature stop codon in the open reading frame of mRNAs are responsible for thousands of inherited diseases. Readthrough of premature stop codons by small molecule drugs has emerged as a promising therapeutic approach to treat disorders resulting from premature termination of translation. The aminoglycoside antibiotics are a class of molecule known to promote readthrough at premature termination codons. Gentamicin consists of a mixture of major and minor aminoglycoside components. Here, we investigated the readthrough activities of the individual components and show that each of the four major gentamicin complex components representing 92-99% of the complex each had similar potency and activity to that of the complex itself. In contrast, a minor component (gentamicin X2) was found to be the most potent and active readthrough component in the gentamicin complex. The known oto- and nephrotoxicity associated with aminoglycosides preclude long-term use as readthrough agents. Thus, we evaluated the components of the gentamicin complex as well as the so-called "designer" aminoglycoside, NB124, for in vitro and in vivo safety. In cells, we observed that gentamicin X2 had a safety/readthrough ratio (cytotoxicity/readthrough potency) superior to that of gentamicin, G418 or NB124. In rodents, we observed that gentamicin X2 showed a safety profile that was superior to G418 overall including reduced nephrotoxicity. These results support further investigation of gentamicin X2 as a therapeutic readthrough agent.